Stents, stenting systems, and related methods for agent delivery

ABSTRACT

A stenting system for insertion into the lumen of a body duct or vessel for delivering a therapeutic agent to a treatment site on the duct or vessel. The stenting system includes an a tubular stent member having a lumen there through to allow the passage of material, an outer membrane attached to the stent at least a portion of which is porous to the therapeutic agent to allow the agent to pass to the treatment site, an inner membrane attached to the stent which is nonporous to the therapeutic agent to prevent the agent from entering the lumen of the stent, and a chamber located between the inner and outer membranes for holding the therapeutic agent. The therapeutic agent in the chamber may diffuse through the porous portion of the membrane and be deposited directly on the body site.

DESCRIPTION OF THE INVENTION

1. Field of the Invention

The present invention relates to a stenting system and, moreparticularly, to a stenting system for delivering therapeutic agents tobody sites. Still more particularly, the present invention relates to astenting system for delivering cellular fluids or other agents to thewalls of a body lumen over a period of time.

2. Background of the Invention

In general, infusion techniques are used to deliver a therapeutic agentto the body. For many medical applications, it is desirable to delivertherapeutic agents, such as drugs or cellular fluids containing culturedcells, directly to a treatment site, such as a duct, vessel, or otherorgan, rather than through general systemic administration.

For example, it may be desirable to treat a duct or organ that hasdeveloped pre-cancerous or cancerous cells directly with a cellular orother therapeutic agent. One such example is in the case of Barret'sesophagus wherein the cell morphology on the surface of the esophagushas changed as a result of chronic gastric reflux of gastric content andacids into the esophagus. This change in cell morphology is oneindicator of potential esophageal cancer. It would be desirable to havea system that treats these cells locally and directly with culturednormal cells to develop normal esophageal cell type.

It may also be desirable to treat other diseased tissues locally anddirectly. For instance, some treatments involve using steroidal ornonsteroidal anti-inflammatory agents, such as in the case of Crohn'sdisease which causes inflammation in the colon, and inflammatory boweldisease. Treatment of the inflamed organs could be more effective if thetreatment was delivered and deposited directly to the target site.

As well, direct apposition of therapeutic agents could reduce the amountof agents that are unnecessarily delivered to the rest of the body andreduce the amount of side effects that may result from the treatment. Inaddition, because the wall of the vessel to be treated may be weakenedby disease or other trauma, it may be desirable to support or protectthe vessel wall as the therapeutic agent is delivered.

Moreover, in many cases, it is desirable to deliver the therapeuticmaterial over a long or indefinite period of time. Thus, it may bedesirable to have a delivery system that does not occlude the targetvessel and can remain at the target site over a long period of time.

SUMMARY OF THE INVENTION

Objects and advantages of the invention will be set forth in thedescription which follows and, in part, will be obvious from thedescription or may be learned by practice of the invention. The objectsand advantages of the invention will be realized and attained by meansof the elements and combinations particularly pointed out in theappended claims.

To achieve the objects and in accordance with the purpose of theinvention, as embodied and broadly described herein, the inventionincludes a stenting system for insertion into a body lumen fordelivering a therapeutic agent to a site on the body lumen. The stentingsystem may include a tubular member having a lumen there through toallow the passage of material, wherein the tubular member may beexpanded causing the stenting system to be retained against the wall ofthe body lumen; an outer membrane surrounding the tubular member,wherein at least a portion of the outer membrane is porous to thetherapeutic agent to allow the therapeutic agent to be deposited on thesite; an inner membrane attached to the tubular member, wherein theinner membrane is non-porous to the therapeutic agent to be delivered tothe site; and a chamber located between the inner and outer membranesfor holding the therapeutic agent, wherein the therapeutic agent in thechamber diffuses through the porous portion of the outer membrane and isdeposited directly on the body site.

According to embodiments of the invention, the stenting system mayinclude an inner tubular member having a lumen there through for thepassage of material; a membrane surrounding the inner tubular member; anouter tubular member surrounding the inner tubular member and themembrane; and a porous member forming at least a portion of the outertubular member, wherein the membrane and the outer tubular member definea chamber there between for holding the therapeutic agent, wherein thetherapeutic agent in the chamber may pass through the porous member ofthe outer tubular member and be deposited directly on the body site, andwherein the membrane is non-porous to the therapeutic agent therebyisolating the lumen of inner tubular member from the therapeutic agentin the chamber.

According to further embodiments of the invention, the stenting systemmay include an expandable tube having a lumen there through, wherein thesides of the tube have openings therein to allow passage of thetherapeutic agent to the body site; an outer membrane surrounding theexpandable tube and forming a chamber with the surface of the expandabletube, wherein at least a portion of the membrane being porous to thetherapeutic agent allowing diffusion of the therapeutic agent therethrough to the body site and wherein the expandable tube prevents thetherapeutic agent from diffusing from the chamber and into the lumen ofthe expandable tube; and an opening in the chamber allowing delivery ofthe therapeutic agent to the chamber, wherein the therapeutic agentdelivered to the chamber diffuses through the porous portion of theouter membrane and is deposited on the body site.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and arenot restrictive of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification. The drawings illustrate embodiments of theinvention and, together with the description, serve to explain theprinciples of the invention.

FIG. 1 is a sectional side view of a stenting system according to apreferred embodiment of the present invention.

FIG. 2 is a cross-sectional side view of a portion of the stentingsystem of FIG. 1. in a body vessel.

FIG. 3 is a cross-section side view of a portion of another stentingsystem according to an embodiment of the present invention.

FIG. 4 is a cross-sectional side view of a portion of another stentingsystem according to a further embodiment of the present invention.

FIG. 5 is a sectional side view of a stenting system according toanother embodiment of the present invention.

FIG. 6 is a cross-sectional side view of another stenting systemaccording to an embodiment of the present invention.

FIG. 7. is a cross-sectional side view of the stenting system of FIG. 6being delivered to a target site, according to an embodiment of thepresent invention.

DESCRIPTION OF THE EMBODIMENTS

Reference will now be made in detail to the present preferredembodiments of the invention, examples of which are illustrated in theaccompanying drawings. Wherever possible, the same reference numbers areused in the drawings and the description to refer to the same or likeparts.

The present invention is directed to systems and methods for deliveringa therapeutic agent to a body duct, vessel, organ, or other body cavityor lumen within the body. The present invention generally includes anexpandable stenting system that can be delivered to the lumen of a bodyduct and expanded to retain the stenting system in the duct and supportand/or protect the walls of the duct. The stenting system includes atubular member, such as a stent, and inner and outer membranes forming achamber there between for holding the therapeutic agent. At least aportion of the outer membrane is formed from a porous material forming aporous membrane. Because the porous membrane of the stenting system isdirectly adjacent to the target vessel or organ when installed, thetherapeutic agent may be delivered directly to and deposited directly onthe target site. Moreover, the stenting system can be left in place foran indefinite period of time because material, including blood, food, orother material, may pass through the stent. Because the stenting systemcan remain in place for an indefinite period of time, as opposed to aballoon or other such delivery mechanism, the therapeutic agent canadvantageously be delivered over a long period of time if necessary.

The stenting systems allow for direct and controlled release of cellularor therapeutic material over time or for immediate delivery. Themembranes of the stenting system can allow a wide range of materials tobe deposited or seeded to the treatment site, including cellularsolutions, drugs, or other treatment material. For instance, thestenting systems according to embodiments of the present invention maybe used to deliver epithelial cell culture to an area of the esophagusthat has been ablated from photo therapy or other cellular destructivetechniques. The stenting systems according to embodiments of the presentinvention provide a mechanism for delivery of cultured cells or othertherapeutic agents to the site of the destroyed cells thereby seedinghealthy cells onto an area having damaged cells. The stenting systemprotects the tissue or cellular area from further damage or cellerosion, while providing a mechanism to further treat the site.

The stenting systems according to other embodiments of the presentinvention may be used to deliver other therapeutic agents to the site.For instance, the stenting systems may be used to deliver cancertreating drugs to the site of a cancerous or precancerous lesion, or maybe used to deliver anti-inflammatory or other agents to a site. Thestenting systems may allow for repeated treatments or agents to bedelivered as desired to achieve the outcome desired. The stentingsystems may be removable such that they may be removed once the cellgrowth process has been completed, the tissue has healed, or thetreatment has otherwise been completed.

Referring to FIGS. 1 and 2, an exemplary stenting system of the presentinvention is shown generally at 10. Stenting system 10 is delivered tothe target site, shown as vessel wall 35 in FIG. 2. Stenting system 10includes a tubular member, an outer membrane 13, an inner membrane 17,and a chamber 25 between membrane 13 and 17 for holding the therapeuticagent. The tubular member is preferably stent 14 having a lumen 19.Preferably, the outer membrane 13 allows passage of the therapeuticagent to the treatment site, and inner member 17 prevents passage of thetherapeutic agent into lumen 19 of the stent 14.

Membrane 13 is designed to allow the therapeutic agent, such as cellularmaterial or agents, to reach the treatment site, and preferablysurrounds the outer surface of stent 14, or at least some portionthereof. To facilitate delivery of the therapeutic agent, at least aportion of membrane 13 is porous to the therapeutic agent, allowing theagent to diffuse through membrane 13 to the target site. Becausemembrane 13 is directly adjacent the vessel wall, the therapeuticmaterial is brought into direct contact with the target vessel and theeffectiveness of the treatment is increased. As well, the amount ofagent diffused to the surrounding tissue or the circulatory, digestive,or other bodily system is minimized, thereby decreasing the amount ofagents that reach healthy tissue.

Membrane 13 is preferably porous over most or all of its surfaces toallow even distribution of the therapeutic agent across the wall of thetarget vessel. It may be desirable, however, in certain applications forless than the entire surface of membrane 13 to be porous. For example,it may be desirable when administering a toxic substance to a tumor tohave only the portion of membrane 13 directly adjacent the tumor beporous. Similarly, in other circumstances it may be desirable to treatonly a portion of the tissue adjacent the stenting system.

Membrane 13 may be porous due to micro holes 15 within the membrane, asshown in FIG. 3 for example. The porosity of the membrane can be therebycontrolled by the size of holes 15 and adapted to the treatment.Preferably, membrane 13 is permeable to oxygen, nitrogen, carbon dioxideand water, as well as the therapeutic agent to be delivered. Forinstance, in the case of treatment using cellular material as thetherapeutic agent, membrane 13 should be permeable to cells of a size ofapproximately 25 micrometers. As previously stated, however, it shouldbe recognized that the desired porosity of the membrane depends on thetreatment being performed and could be adapted to various treatments.Moreover, by controlling the size of holes 15, membrane 13 can provide acontrolled release of the therapeutic agent.

Membrane 13 is preferably elastomeric, allowing it to conform to thelumen or organ walls for greater apposition of the therapeutic agent tothe target site and less damage to the target site. Materials providingsuitable porosity and softness include polyolefin, polypropylene,polyethylene, and polycarbonate. Membrane 13 may be spun from thesematerials and the porosity selected based on the treatment to beperformed. Other suitable materials that provide the appropriateporosity may be used. Alternatively, micro holes could be provided inmore rigid material, such as silicon or polyurethane, or rubber, such asethylene vinyl acetate, through drilling with a laser or otherwise orother method of providing small precise holes. Outer member 13 could bea rigid or expandable tubular member.

As an alternative, the outer membrane may be made porous by a loose meshconstruction as shown at 23 in FIG. 4. In this case, stent 14 is shownembedded in a mesh membrane 44 and membrane 17 is located on the innersurface of stent 14. Cells or other therapeutic agents are shown at 40between the stenting system and vessel wall 35. Further, membranes 13and 23 may be coated or impregnated with hyaluranic acid or othersuitable substance to prevent tissue growth into the membrane.

Membrane 13 may be adhesively bound to membrane 17 and stent 14 as shownin FIGS. 2 and 3 or can be attached to membrane 17 and stent 14 throughother suitable means. As shown in FIG. 2, membrane 13 may be adhereddirectly to inner member 17 at one end and adhered to a flexible tubing27, which allows for the passage of the therapeutic agent. Adhesive 21may be applied at the ends 12 of membrane 13. The adhesive portionsattaching membrane 13 to membrane 17 and tubing 27 preferably rendermembrane 13 non-porous at ends 12 such that the therapeutic agent cannotpass through membrane 13 in the areas of the adhesive portions at ends12. It should be recognized that membrane 13 may be attached or securedto either or both of membrane 17 or stent 14 at each end, attached totubing at each end, or otherwise attached to structure that formschamber 25 between membrane 13 and 17.

Inner membrane 17 preferably is designed to prevent the therapeuticagent from passing into lumen 19 of stent 14. As a result, membrane 17is preferably non-porous to the therapeutic agent. Membrane 17 is alsopreferably elastomeric and permeable to oxygen, nitrogen, and carbondioxide while being non-permeable to HCL and hydrogen ions. Membrane 17should further be non-reactive to acid and non-toxic. Suitable materialsinclude butadiene or ethylene vinyl chloride, or other appropriatematerials. Alternatively, membrane 17 could be non-permeable to allfluids and gas, and made from silicon, polyurethane, or other suitablematerial.

Membrane 17 may be adhesively bonded to stent 14 by adhesive 22, asshown in FIG. 2, or attached to stent 14 through other suitablemechanisms. While membrane 17 is shown attached to the outer surface ofstent 14, it should be recognized that membrane 17 could be located onthe inner surface of stent 14 or that stent 14 could be embedded inmembrane 17, as shown in FIG. 3. Alternatively, it could be possible toeliminate membrane 17 if the walls of stent 14 are solid with noopenings, thereby preventing the therapeutic agent from entering lumen19.

Membrane 17 also preferably is bonded to membrane 13 at one end of stent14 and bonded to tubing 27 at the other end of stent 14, as shown inFIG. 2. As described above, it should be recognized that membrane 17 canbe attached to membrane 13 at each end, attached to tubing at each end,or otherwise attached to structure that forms chamber 25 betweenmembrane 13 and 17.

Stent 14 is generally a tubular member, although it may take differentforms depending on the target vessel or lumen. For instance, stent 14may have many known tubular shapes, such as an indented tube as shown inFIGS. 1 and 2. Alternatively, for example, the stent 14 could be astraight tubular member, as shown at 140 in stenting system 100 shown inFIG. 5.

Stent 14 may be any of the types well known in the art. For instance,stent 14 may be an expandable type stent that expands radially outwardlyfrom a first position, wherein the stent passes through the body lumenor target vessel, to a second expanded position, wherein stent 14 isretained against the wall of the body lumen or other target vessel.Stent 14 may be formed from many known stent constructions, such ascross-hatched or mesh filaments or interlocking loops. The initial sizeof stent 14 depends on the shape and size of the target vessel. Stent 14preferably is sized such that the stenting system can be inserted into atarget vessel and can be expanded such that the stenting system isretained against the vessel wall.

Stent 14 may be expanded through known means such as by a balloon, orany other device capable of expanding stent 14, deployed through thelumen 19 of stent 14. The stenting system could be delivered to thetarget site over a balloon catheter. Once at the target site, theballoon could be inflated causing stent 14 to expand. The balloon maythen be deflated, and stenting system 10 is retained in the lumenagainst the target vessel wall. When in place, blood, fluids, or othermaterial may pass freely through lumen 19 of stent 14. In this case,stent 14 can be made from high or low molecular weight stainless steelor other suitable material.

Alternatively, stent 14 may be of the self-expanding type, that is onethat has mechanical memory such that it can return to a preformed shapeafter it has been compressed or deformed. In such a case, the tube isinitially configured in its final desired shape. The tube is thencontracted by deforming the tube or by constraining the tube using anyof several techniques known in the art. The tube can remain in thiscontracted state until it is delivered to the target vessel where it isallowed to expand to its initial state.

Further, eye holes 30 may be provided on the ends of stenting system 10,as shown in FIG. 3, providing an easy means to grasp hold of thestenting system for placement and removal. The eye holes 30 can begrasped and the stenting system elongated for placement and removal ofthe stenting system.

In the embodiment of a self-expanding stent, stent 14 preferably is madefrom an alloy having shape retaining properties such as a high or lowmolecular weight nickel and titanium alloys, commonly known as nitinolalloys, PLLA, PGA, or other suitable substances. Stent 14 is initiallyformed in its end desired shape. The shape and size of stent 14 dependson the shape and size of the target lumen or vessel. The stent 14 may beshaped such that after stenting system 10 has been inserted into thetarget vessel, the stenting system is slightly larger than the lumen ofthe target vessel so that stenting system is retained against the vesselwall.

In another embodiment of the present invention, as shown in FIGS. 6 and7, stenting system 10 may be retained in the target vessel through useof tissue adhesives. Adhesives 33 may be applied at the ends of thestenting system, along membranes 13 or 23, preferably for a length of0.5 to 1 micronmeter. The adhesives may be applied to membrane 13 orimpregnated into membrane 23. Adhesives such as hyaluronic acid or thoseuse on self-stick, repositionable note pads, or other suitableadhesives.

In this embodiment, the stenting system could be deployed within asheath 36 made from a material, such as Teflon, that does not adhere tothe adhesive. As shown in FIG. 8, the stenting system may be introducedto the target site with sheath 36. When sheath 36 is removed (by, forexample, moving if proximally relative to the stenting system), thestenting system will expand and adhesive 33 can retain the stentingsystem along the vessel walls 35. The tissue adhesive may be used alone,thereby reducing the mechanical forces on the lumen, or in conjunctionwith other methods of retaining the stenting system in place such asballoon expanded stents or self-expanding stents to help prevent stentmigration.

Stenting system 10 may be delivered to the target site with a catheter,endoscope, or other conventional delivery techniques. For instance,stenting system 10 can be delivered through the working channel of anendoscope positioned at the target lumen or organ. Stenting system 10may be delivered with a guide wire or a balloon catheter to the targetsite. In the case of the balloon catheter, stenting system 10 may bedelivered over the balloon and expanded by the balloon so that stentingsystem 10 supports the vessel or organ wall. After the stenting system10 has been delivered, the catheter, guide wire, or other deliverymechanism may be withdrawn.

Stenting system 10 further preferably has an opening 23 at one end 21 ofchamber 25 for delivering the therapeutic agent to chamber 25, as shownin FIG. 1. The other end 29 of chamber 25 is preferably sealed, but maybe provided with an opening or a sealable opening. Stenting system 10also preferably has a flexible tube 27 attached to membranes 13 and 17at opening 23, or other delivery means in communication with chamber 25for delivering the therapeutic agent to the chamber. It should berecognized that other delivery mechanisms could be used such as a needleinserted into a frangible member provided at opening 23. Moreover, italso should be recognized that there may be instances in which it ispreferable to have delivery means connected to both ends of chamber 25,or, alternatively, to have both ends of chamber 25 sealed. If both endsof chamber 25 are sealed, the agent may be provided in the chamber priorto sealing of the chamber or the agent may be delivered into the chamberthrough a needle inserted into the chamber or other delivery mechanism.

The therapeutic agent of interest may be delivered to opening 23 in thestenting system 10 through flexible tubing 27, an endoscope, catheter,or other conventional delivery systems. If a single delivery of an agentis desired, such as in the case of genetic material or cancer treatingagent, the delivery system can be removed after the material has beendelivered. If constant delivery of a material over a period of time isdesired, such as for the delivery of cellular material or a low level ofmedication over a period of time, the tubing 27 can be provided or otherdelivery system can remain docked to the stenting system to providematerial delivery. Moreover, if multiple or repeated deliveries of asubstance are desired, the delivery system can be re-introduced todeliver the material to opening 23.

As an alternative to leaving flexible tubing 27 or other delivery systemdocked at stenting system 10, and as an alternative to repeatingdeliveries of a therapeutic agent to stenting system 10, the therapeuticagent could be prepared such that it releases at a low level over anextended period of time. Specifically, the therapeutic agent could bemixed with an extended release polymer resulting in delivery of a lowlevel of the agent for weeks or months or longer. One such extendedrelease polymer is ethyl vinyl acetate which provides a good deliverymedium for a polyolefin tube and causes the agent to be delivered overan extended period of time. Similarly, as discussed above, the porosityof membrane 13 may be adjusted to provide controlled release of thetherapeutic agent.

Stenting system 10 also may be provided with a valve 31 located at theend of flexible tubing 27, as shown in FIG. 2, to prevent back flow ofthe therapeutic agent. Alternatively, valve 31 could be located directlyat opening 23. The valve could be a conventional duck bill valve,elastomeric valve, or any other suitable valve. If the therapeutic agenthas a high viscosity such that not much of the agent escapes throughopening 23, a valve may not be necessary. On the other hand, if thetherapeutic agent has a low viscosity, it may be desirable to use avalve to prevent the agent from back flowing through tubing 27 oropening 23.

Moreover, the extent to which a valve is used may depend on the agentbeing delivered and the delivery mechanism. In certain applications,such as with delivering an anti-inflammatory substance, it may not becritical to prevent the escape of the therapeutic agent through opening23. Whereas in other applications, such as with cancer fighting agents,it may be more desirable to prevent the escape of any of the agentthrough opening 23. In addition, certain delivery mechanisms may havemeans to prevent any escape of the agent through opening 23, and in suchinstance a valve would be unnecessary.

The stenting system of the present invention may be used in a number ofsituations. For example, it may be used in the replacement of abnormalor damaged cells in the alimentary and/or pulmonary tracts, such as inthe case of Barrett's esophagus. In such a treatment, the abnormal cellsare killed or removed from the tissue and normal cells are cultured anddelivered to the diseased or damaged site in an effort to regrow normalcell tissue. The stenting system of the present invention may be usedboth to remove the abnormal cells and to deliver the cultured cells tothe site.

Stenting system 10 may be delivered to the target site with an agentthat will remove or burn off the surface layer of cells in the abnormalregion. Normal cells that have been cultured and mixed with a growthmedium may then be introduced into the port in the stenting system andinto the material holding chamber. The cells are then delivered throughporous outer tube directly to the damaged body tract to enhance healingand new normal cell growth. Stenting system 10 also provides aprotective environment to allow the cells to grow back as a normal celltype. Further, stenting system 10 allows for the passage of othermaterials, such as food, through the lumen 19 of the stent 14 and cantherefore be used in place for an extended period of time.

Stenting system 10 may also be used to repair damaged cellular membranesas a result of chemicals, chemotherapy, radiation, or inhalation oftoxic compounds. The stenting system may also be used to deliver a drugto a body site. The stenting system of the present invention is notlimited to the applications specifically described herein but may beused in a number of other situations.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the structure andmethodology of the present invention without departing from the scope orspirit of the invention. In view of the foregoing, it is intended thatthe present invention cover modifications and variations of thisinvention that fall within the scope of the following claims and theirequivalents.

1. A system for insertion into a body lumen for delivering an agent to asite on the body lumen, the system comprising, a tubular member having alumen there through to allow the passage of material, wherein thetubular member may be expanded causing the stenting system to beretained against the wall of the body lumen; an outer membranesurrounding the tubular member, wherein at least a portion of the outermembrane is porous to the agent to allow the agent to be deposited onthe site; an inner membrane attached to the tubular member, wherein theinner membrane is non-porous to the therapeutic agent to be delivered tothe site; and a chamber located between the inner and outer membranesfor holding the agent, wherein the agent in the chamber diffuses throughthe porous portion of the outer membrane and onto the body site.
 2. Thesystem according to claim 1, further comprising an opening in thechamber for delivery of the agent to the chamber.
 3. The systemaccording to claim 2, further comprising a one-way valve in the openingpreventing the agent from exiting the chamber through the valve.
 4. Thesystem according to claim 1, wherein the inner membrane prevents theagent in the chamber from entering the lumen of the tubular member. 5.The system according to claim 1, wherein the tubular member is formedfrom a material that can return to its initially formed shape afterdeformation.
 6. The system according to claim 1, wherein the tubularmember is capable of being expanded by a balloon inserted into the lumenof the tubular member.
 7. The system according to claim 1, wherein theouter membrane is flexible such that it may conform to the shape of thebody lumen.
 8. The system according to claim 1, further including atubing in communication with the chamber for introducing to the agentinto the chamber.
 9. A system for insertion into a body lumen fordelivering an agent to a site on the body lumen, the system comprising,an inner tubular member having a lumen there through for the passage ofmaterial; a membrane surrounding the inner tubular member; an outertubular member surrounding the inner tubular member and the membrane;and a porous member forming at least a portion of the outer tubularmember, wherein the membrane and the outer tubular member define achamber there between for holding the agent, wherein the agent in thechamber may pass through the porous member of the outer tubular memberand be deposited directly on the body site, and wherein the membrane isnon-porous to the agent thereby isolating the lumen of inner tubularmember from the agent in the chamber.
 10. The system according to claim9, further comprising balloons located at each end of the outer tubularmember, wherein the balloons can be expanded to retain the systemagainst a wall of the lumen.
 11. The system according to claim 9,wherein the inner tubular member is capable of being expanded such thatwhen it is expanded the system is retained against the lumen wall. 12.The system according to claim 11, wherein the inner tubular member isformed from a material that can return to its initially formed shapeafter deformation.
 13. The system according to claim 11, wherein theinner tubular member is capable of being expanded by a balloon insertedinto the lumen of the inner tubular member.
 14. The system according toclaim 9, further including a tubing in communication with the chamberfor introducing the agent into the chamber.
 15. The system according toclaim 9, further comprising an opening in the chamber for delivery ofthe agent to the chamber.
 16. The system according to claim 11, furthercomprising a one-way valve in the opening preventing the agent fromexiting the chamber through the valve.
 17. A system for delivering anagent to a body site comprising: an expandable tube having a lumen therethrough, wherein the sides of the tube have openings therein to allowpassage of material through the lumen; an outer membrane surrounding theexpandable tube and forming a chamber with a surface of the expandabletube, wherein at least a portion of the membrane is porous to the agentallowing diffusion of the agent there through to the body site, andwherein the expandable tube prevents the agent from diffusing from thechamber and into the lumen of the expandable tube; and an opening in thechamber allowing delivery of the agent to the chamber.
 18. The accordingto claim 17, further comprising an inner membrane attached to theexpandable tube, wherein the inner membrane is non-porous to the agentand prevents the agent in the chamber from entering the lumen.
 19. Thesystem according to claim 17, further comprising a one-way valve locatedin the opening preventing the agent from exiting the chamber through thevalve.
 20. The system according to claim 17, wherein the tube is formedfrom a material that can return to its initially formed shape afterdeformation.
 21. The system according to claim 17, wherein the tube isexpanded against the body site by a balloon catheter introduced throughthe lumen of the inner tube.
 22. The system according to claim 17,further comprising tissue adhesives located along a portion of the tubefor retaining the tube at the body site.